uhttp lua

2016-12-05 Kommentare openwrt

uhttp lua

uhttp-mod-lua

  • 安裝 uhttpd-mod-lua
  • 透過 uci 設定
  • 重啟 uhttpd
安裝 uhttpd-mod-lua
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opkg update
opkg install uhttpd-mod-lua
uci set uhttpd.main.lua_prefix=/lua
uci set uhttpd.main.lua_handler=/root/test.lua
uci commit uhttpd
/etc/init.d/uhttpd restart
wget -qO- http://127.0.0.1/lua/

這份 lua file，比較要注意的地方是

  • 回呼函數名稱一定要是 handle_request
  • 未定義但是可以用的變數 uhttpd
test.lua
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function handle_request(env)
    uhttpd.send("Status: 200 OK\r\n")
    uhttpd.send("Content-Type: text/plain\r\n\r\n")

--[[
    env 底下的 key，以及對應型態
    REQUEST_METHOD (String)
    REQUEST_URI (String)
    SCRIPT_NAME (String)
    QUERY_STRING (String)
    PATH_INFO (String)
    HTTP_VERSION (Number)
    SERVER_PROTOCOL (String)
    REMOTE_ADDR (String)
    REMOTE_PORT (Int)
    SERVER_ADDR (String)
    SERVER_PORT (Int)
    CONTENT_LENGTH (Number)
    CONTENT_TYPE (String)
    headers (Table)
--]]

    uhttpd.send("REQUEST_METHOD".." "..tostring(env.REQUEST_METHOD).."\n")
    uhttpd.send("REQUEST_URI".." "..tostring(env.REQUEST_URI).."\n")
    uhttpd.send("SCRIPT_NAME".." "..tostring(env.SCRIPT_NAME).."\n")
    uhttpd.send("QUERY_STRING".." "..tostring(env.QUERY_STRING).."\n")
    uhttpd.send("PATH_INFO".." "..tostring(env.PATH_INFO).."\n")
    uhttpd.send("SERVER_PROTOCOL".." "..tostring(env.SERVER_PROTOCOL).."\n")
    uhttpd.send("REMOTE_ADDR".." "..tostring(env.REMOTE_ADDR).."\n")
    uhttpd.send("SERVER_ADDR".." "..tostring(env.SERVER_ADDR).."\n")
    uhttpd.send("CONTENT_TYPE".." "..tostring(env.CONTENT_TYPE).."\n")

    uhttpd.send("HTTP_VERSION".." "..tostring(env.HTTP_VERSION).."\n")
    uhttpd.send("REMOTE_PORT".." "..tostring(env.REMOTE_PORT).."\n")
    uhttpd.send("SERVER_PORT".." "..tostring(env.SERVER_PORT).."\n")
    uhttpd.send("CONTENT_LENGTH".." "..tostring(env.CONTENT_LENGTH).."\n")

    uhttpd.send("Headers start\n")
    uhttpd.send("-------------\n")
    for k,v in pairs(env.headers) do
        uhttpd.send(k.." "..v.."\n")
    end 
    uhttpd.send("-------------\n")

    local len,data = uhttpd.recv(1024)
    if len > 0 then
        uhttpd.send("length:"..tostring(len).."\n")
        uhttpd.send("data:"..data.."\n")
    end

    uhttpd.send("Hello world.\n")

end

uhttpd-lua.h

再回來看 uhttpd-lua.h， 提供給 lua 當回乎函數 handle_request 似乎有點著落

uhttpd-lua.hlink
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#define UH_LUA_CALLBACK         "handle_request"

lua_State * uh_lua_init();

void uh_lua_request(
        struct client *cl, struct http_request *req, lua_State *L
);

void uh_lua_close(lua_State *L);

uhttpd-lua.c

從這邊可以看到 lua_setfield(L, LUA_GLOBALSINDEX, "uhttpd");，提供 lua 全域變數 uhttpd (table)，並提供以下欄位

  • recv (Int -> (Int,String))
  • send (String -> Int)
  • sendc (String -> Int)
  • urldecode (String -> String)

c 的動作 ：

  • luaL_loadfile(L, handler) 把 handler 當成 function 載入，並把 function 放入堆疊 (handler=/root/test.lua)
  • lua_pcall(L, 0, 0, 0) 執行堆疊上第一個，0,0,0 分別是 輸入參數個數,return 個數,錯誤處理 function
  • lua_getglobal(L, UH_LUA_CALLBACK)，將 handle_request 放入堆疊
  • lua_isfunction(L, -1)，確認堆疊最上層是 function
c 調用 lua function
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-- lua_pcall(L, 2, 3, 0)
-- |      y      | 3
-- |      x      | 2
-- | function xy | 1

function xy (x,y)
    return x,y,x+y
end
uhttpd-lua.clink
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lua_State * uh_lua_init(const char *handler) {
    lua_State *L = lua_open();
    const char *err_str = NULL;

    /* Load standard libaries */
    luaL_openlibs(L);

    /* build uhttpd api table */
    lua_newtable(L);

    /* register global send and receive functions */
    lua_pushcfunction(L, uh_lua_recv);
    lua_setfield(L, -2, "recv");

    lua_pushcfunction(L, uh_lua_send);
    lua_setfield(L, -2, "send");

    lua_pushcfunction(L, uh_lua_sendc);
    lua_setfield(L, -2, "sendc");

    lua_pushcfunction(L, uh_lua_urldecode);
    lua_setfield(L, -2, "urldecode");

    /* _G.uhttpd = { ... } */
    lua_setfield(L, LUA_GLOBALSINDEX, "uhttpd");
// ...
    switch( luaL_loadfile(L, handler) ) {
    default:
        /* compile Lua handler */
        switch( lua_pcall(L, 0, 0, 0) ) {
        default:
            /* test handler function */
            lua_getglobal(L, UH_LUA_CALLBACK);

            if( ! lua_isfunction(L, -1) ){
                    fprintf(stderr,
                            "Lua handler provides no " UH_LUA_CALLBACK "(), unable to continue\n");
                    exit(1);
            }

            lua_pop(L, 1);
            break;
        }
        break;
    }
    return L;
}

uhttpd.c

  • 解析 arg
  • 透過 -c 讀取 config 檔案(或預設位置 /etc/httpd.conf)
  • 讀取 so 檔案，(dlopen("uhttpd_lua.so", RTLD_LAZY | RTLD_GLOBAL))
  • 執行 uhttpd-lua.c 的 lua_init
uhttpd.c
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static void uh_config_parse(struct config *conf)
{
// ...
    const char *path = conf->file ? conf->file : "/etc/httpd.conf";
// ...
}

int main (int argc, char **argv)
{
// ...
    /* init Lua runtime if handler is specified */
    if( conf.lua_handler )
    {
            /* default lua prefix */
            if( ! conf.lua_prefix )
                    conf.lua_prefix = "/lua";

            conf.lua_state = conf.lua_init(conf.lua_handler);
    }
// ...
}

uhttpd

/etc/init.d/uhttpd
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# lrwxrwxrwx    1 root     root            16 Nov 20  2015 S50uhttpd -> ../init.d/uhttpd
start_service() {
	config_load uhttpd
	config_foreach start_instance uhttpd
}

start_instance() {
    local cfg="$1"
# ...
    append_arg "$cfg" config "-c"
}

append_arg() {
	local cfg="$1"
	local var="$2"
	local opt="$3"
	local def="$4"
	local val

	config_get val "$cfg" "$var"
	[ -n "$val" -o -n "$def" ] && procd_append_param command "$opt" "${val:-$def}"
}

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